A standard microbiological panel for spices covers total plate count (TPC), yeast and mould, coliforms or E. coli, and Salmonella, which buyers usually require to be absent in 25 g. Many food manufacturers add Bacillus cereus, Clostridium perfringens or sulphite-reducing clostridia, and Staphylococcus aureus.
Apart from Salmonella, most of the limits come from your customer's specification rather than from law. They depend on the spice and on whether it will be cooked after use.
What each test tells you
- Total plate count (also called aerobic plate count): the overall level of bacteria. A general measure of hygiene and treatment, reported in cfu/g.
- Yeast and mould: a sign of damp conditions in drying or storage, and a warning for mycotoxin risk.
- Coliforms and E. coli: indicators of faecal contamination and poor hygiene in handling.
- Salmonella: a pathogen. Its presence makes the product unsafe and is a common reason for EU and US rejections.
- Bacillus cereus and Clostridium perfringens: spore-forming bacteria that survive drying and can multiply in cooked food left warm.
- Staphylococcus aureus: an indicator of contamination from people handling the product.
Methods to ask for
Ask for ISO methods or equivalent validated methods within the lab's accredited scope. Common references include ISO 4833 for plate count, ISO 21527 for yeast and mould, ISO 16649 for E. coli and ISO 6579 for Salmonella. US buyers may ask for FDA Bacteriological Analytical Manual methods instead. Whatever you choose, write the method into the spec so origin and destination labs test the same way.
Setting limits in your spec
Limits for TPC and yeast and mould vary widely. A spice sold to a meat processor or a ready-to-eat snack maker needs much lower counts than one going into a product that is boiled. Ask your customer for their limits. Use any figure from a supplier's standard spec only as an illustration, not as your limit.
Raw spices from the field often carry high counts. Where your customer needs low counts, the spice must be treated, most often by steam sterilisation. See what steam sterilisation is and when you need it.
Sampling and timing
- Draw micro samples with clean, sterile tools into sterile bags, separately from chemical samples.
- Test after sterilisation and packing, not before.
- Check that sterilised product is packed in a clean area, away from raw material.
- Allow time: Salmonella results include an enrichment and confirmation step and take longer than counts.
- For powders such as onion and garlic, see why salmonella appears in dehydrated onion.
How we help
We agree the micro panel and limits with you, draw sterile samples from the packed lot and send them to an NABL-accredited lab. Where you need steam-sterilised product, we check the sterilisation line and post-treatment handling during the audit. Ask for a free sourcing review.